Corrugated insert cutting apparatus and method

ABSTRACT

An insert cutting apparatus useable in a production line for producing tubes from shaped sheet-metal strips includes an upper die having a first row of punches, and a lower die having a second row of punches. The first and second rows of punches can form predetermined breaking points in at least one of the shaped sheet-metal strips, and the first and second rows of punches can alternate, so that two punches of the first row of punches have a punch of the second row of punches therebetween.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to German Patent Application No. 10 2010 022 713.7 filed Jun. 4, 2010, the entire contents of which are hereby incorporated by reference herein.

BACKGROUND

The invention relates to a device, for example as part of a production line for producing tubes from shaped sheet-metal strips. Furthermore, the invention relates to a method for producing tubes.

In DE 10 2007 028 710 A1, perforations or predetermined breaking points are formed following the shaping of sheet-metal strips a, b, c, for simplifying alignment of the perforations or predetermined breaking points in the sheet-metal strips a, b, c (see attached FIGS. 1 and 2). According to this reference, the transverse corrugation 100 of the inner insert c is destroyed by creation of the perforations, and has to be reworked, which is disadvantageous. With the production method from the abovementioned publication, flat tubes, as illustrated in the form of a cross section through the flat tube in FIG. 2, are produced. The webs 12 (shown hatched) remaining on the longitudinal edges of the sheet-metal strip (FIG. 2) are severed later by means of a separating device in order to produce individual flat tubes, in particular for heat exchangers. The waves of the transverse corrugation 100 run in a transverse direction of the sheet-metal strip. In the finished flat tube, the transverse corrugation 100 provides flow ducts running in the longitudinal direction for a heat-exchanger, said flow ducts being visible in FIG. 2.

In DE 196 41 144 A1, in GB 2 203 677 A and in U.S. Pat. No. 2,222,842, notchings are made in a single sheet-metal strip. The sheet-metal strip is still flat, i.e. still not deformed, at the time the notchings are created.

SUMMARY

It is an object of the invention to propose a highly suitable device with which a sheet-metal strip which is already shaped, for example a flat tube inner insert provided with a transverse corrugation, or the flat tube itself, can be perforated or provided with predetermined breaking points without the transverse corrugation or the shaping being destroyed. Furthermore, a method for producing tubes is provided, with which the preparation costs for a production line can be reduced.

In some aspects, the device has at least one row of punches in each case in the upper die and in the lower die. In each case, two punches of one row can have a punch of the other row arranged therebetween. In some embodiments, at least one of the sheet-metal strips is provided with a transverse corrugation, and one row of punches acts on the wave crests and the other row of punches acts on the wave troughs. The device can be part of a production line for producing tubes. However, the device may also serve to produce individual deformed sheet-metal strips which are suitable for purposes other than producing tubes.

Furthermore, the device can also be used to perforate complete flat tubes in order to cut the latter to a predetermined length. In this case, the shaped sheet-metal strip should be interpreted as being the flat tube. The production method according to some embodiments of the invention therefore also makes provision to create perforations or predetermined breaking points into the tube which has already been produced, with at least one row of punches from one side and another row of punches from the opposite side being pierced through the tube, and in each case, two punches of one row have a punch of the other row engaging therebetween. This saves on separate devices and systems for orienting the perforations or predetermined breaking points in the sheet-metal strip. The punches may be cutting or stamping punches. In some embodiments, at the moment of producing the perforations or predetermined breaking points, the abovementioned row of punches in the one (e.g. upper) die together with the row of punches in the other (e.g. lower) die lie exactly in one plane—transversely with respect to the longitudinal direction of the sheet-metal strip—so that separating points which are as rectilinear as possible can be produced at the ends.

In some embodiments, the punches in the rows of punches are designed as needles or similar slim piercing tools. The use of such piercing tools results in the wave crests and the wave troughs being pierced. Short webs can be retained in the wave flanks and on the longitudinal edges of the sheet-metal strip, said webs being separated later, i.e. during the severing of individual flat tubes at the end of the production line.

Provision is furthermore made for the needles of one (e.g. upper) die to pierce the wave troughs and needles of the other (e.g. lower) die to pierce the wave crests. With some embodiments of the device, the wave flanks are subjected to a tensile stress during the piercing of the wave crests/wave troughs, and therefore there need be no concern at the same time that the corrugation will be deformed, even when using tools edge lives that have already been exceeded.

Some embodiments utilize a device having one (e.g. upper) die and the another (e.g. lower) die formed with a matching wave shape, wherein the shaped sheet-metal strip is severed or adequately notched at least in the corrugated region. Accordingly, by means of some embodiments, perforations are produced, and the entire corrugated region of the sheet-metal strip is notched or cut into with this device.

According to some embodiments, the transverse corrugation of the sheet-metal strip is maintained, that is to say, the wave shape does not have to be restored by reworking, as is necessary in the prior art described above.

In some embodiments, a pair of rolls, for example, is used as the dies (e.g. the upper and lower dies).

The device according to some embodiments cooperates with other devices from the prior art described above in such a manner that all of the devices are activated at the same time. In contrast to the prior art shown in FIG. 1, all of the devices can be located at a common point of the production line, downstream of the shaping process and upstream of the process of combining the three sheet-metal strips to form the flat tube, for example at the point denoted in FIG. 1 by P1. The device P2 of FIG. 1 corresponds to the sheet-metal strip a, and the device P3 provides perforations/predetermined breaking points in the sheet-metal strip b. Since, during standard operation of the production line, the sheet-metal strips pass through the latter at a relatively high, but identical speed (100-200 m/min), the need for orienting the perforations/predetermined breaking points in the three sheet-metal strips can be reduced further or rendered entirely superfluous.

BRIEF DESCRIPTIONS OF THE DRAWINGS

FIGS. 1 and 2 show an item of prior art, FIG. 1 showing a roll train (production line) in principle and FIG. 2 depicting a view of one end of the flat tubes produced therewith.

FIG. 3 shows an enlarged partial cross section of the device according to some embodiments of the invention.

FIG. 4 shows a perspective view of a device according to some embodiments of the invention.

FIGS. 5 a-5 f show details of a device according to some embodiments of the invention.

FIGS. 6 a and 6 b show an alternative device design according to some embodiments of the present invention.

FIG. 7 schematically shows the arrangement of a plurality of devices in the production line.

FIG. 8 shows the first device according to an embodiment of the present invention, used for perforating complete tubes.

DETAILED DESCRIPTION

In the first exemplary embodiment of a device P1 according to the present invention, a pair of rollers is used as an upper die O and a lower die U, as can best be seen from FIG. 4.

In other embodiments (not shown), rather than a pair of rollers, use is made of two rams which are vertically movable, for example, by means of eccentric shafts and to which rows of punches are fastened, as described below. The abovementioned pair of rolls or the device P1 can be part of a production line (shown in FIG. 1) for producing flat tubes, and can be located approximately at the position denoted by P1. Other devices P2 and P3 can also be located at the same position H, this being indicated in FIG. 7. The other devices P2 and P3 can be devices for inserting perforations or predetermined breaking points in other sheet-metal strips a and b. The other devices P2 and P3 are configured in a manner which is suitable but is not shown, in order to fulfill the abovementioned purpose. In this exemplary embodiment, the devices are not identical in terms of the construction thereof with the device P1 described further below. In contrast to the schematic illustration in FIG. 7—the devices P1, P2 and P3 can be combined in a single composite tool, this merely being indicated by means of the border shown by dashed lines. All of these devices in FIG. 7 P1, P2, P3 are activated at the same time. FIG. 4 shows the pair of rolls of the device P1 in the action position, i.e. in the position in which the perforations or predetermined breaking points are produced in the sheet-metal strip c formed with a transverse corrugation 10. In the standby position (not shown), the rows of punches 20 can be located in a position rotated through 180°, i.e. the row of punches of the upper roll O point upward and the row of punches of the lower roll point correspondingly downward. However, a plurality of rows of punches 20 can be arranged both in the upper die O and in the lower die U. For example, three rows of punches could be distributed around the circumference of the rolls (not illustrated). This can enable a required die change to be delayed or the service life of the die to be extended.

According to FIG. 4, the upper roll O and the lower roll U have respective guide rings 21, 22 for guiding the deformed sheet-metal strip c passing therethrough while the rolls O, U are in the position. Instead of the one deformed sheet-metal strip c, the material passing through the rolls O, U may optionally be the flat tube 1 to be perforated. As can be seen, the lower ring 22 guides the longitudinal edge of the sheet-metal strip c or of the tube 1 which is on the left in the drawing and the upper ring 21 correspondingly guides the right longitudinal edge. The direction of movement of the sheet-metal strip c or of the tube 1 is indicated by means of an arrow in FIG. 4.

FIG. 3 also shows the action position in a significantly enlarged detail from FIG. 4. It can be seen therefrom that, in the action position, two punches 20 of the one (upper) row of punches in each case has a punch 20 of the other (lower) row of punches located therebetween. The deformed sheet-metal strip c can also be seen in FIG. 3. The sheet-metal strip c is designed with the transverse corrugation 10 (see FIG. 6 b). Furthermore, it is apparent that the (upper) set of punches 20 acts on the wave troughs 15 and the other (lower) set of punches 20 acts correspondingly on the wave crests 11. Since, in this exemplary embodiment, the punches 20 are piercing tools, in particular perforation needles, the wave troughs 15 and the wave crests 11 are pierced by the needles. A further perforation needle can also be provided on the longitudinal edges of the sheet-metal strip c in order to configure the width of the webs 12 (FIG. 2) so as to meet requirements. Furthermore, with reference to FIG. 3, in some embodiments the wave flanks 13 extending between the wave crests 11 and wave troughs 15 are subjected to a tensile stress during the production of the perforations or at least are not compressed, and therefore the wave shape 10 is maintained. However, it goes without saying here that it is not only the wave crests and wave troughs which are pierced in some embodiments, since in such embodiments the piercings can reach into the wave flanks 13. The connecting webs remaining approximately centrally in the wave flanks 13 have not been depicted in the drawings.

FIGS. 5 a-5 f depict details of the lower roll U, said details expediently also being present on the upper roll O. FIGS. 5 a-5 c show a front view, a side view and a top view of the abovementioned roll U. The row of punches 20 (perforation needles) can be seen in FIG. 5 b. FIG. 5 d shows the section C-C from FIG. 5 b. Clamping jaws 23 and 24 (see FIG. 5 e), with which the punches 20 are held in the lower roll U and in the upper role O, can be seen therefrom. FIGS. 5 e and 5 f show further details in this regard. The reference number 25 denotes an elastic insert which can advantageously be used to releasably hold the punches 20. In a similar manner, the punches 20 could also be fastened to rams, which are explained above but which are not shown and which can optionally form an upper die O and a lower die U.

FIGS. 6 a and 6 b show an alternative exemplary embodiment with regard to device P1, wherein FIG. 6 a shows only an upper die O and a lower die U, and FIG. 6 b additionally shows the deformed sheet-metal strip c running therebetween. In this embodiment, the lower die U can likewise be a rotating roll. By contrast, the illustrated upper die O is a knife or the like which is formed with a wave contour and is arranged approximately centrally above the roll U. The knife can be moved upward and downward, for example by means of an eccentric shaft (not shown). The illustrated wave shape 10 is present in both dies. The upper die O, in the lower position thereof, severs the sheet-metal strip c without destroying the corrugation 10 thereof. Webs 12 are retained on both longitudinal edges.

The dimensions D, d (FIG. 2) of the flat tubes 1 to be produced may differ, since they are directed, for example, towards the intended use of a heat exchanger equipped therewith. For example, the wave height d of the corrugated sheet-metal strip c, which wave height approximately corresponds to the inner tube height, can be approximately 1.3 mm although shorter and longer wave lengths are possible. The sheet-metal thickness of the sheet-metal strip is, for example, between 0.06 mm—or somewhat more—for the corrugated sheet-metal strip c, and up to a maximum of 0.20 mm for the sheet-metal strips a, b forming the wall parts of the flat tube 1. The device P1 according to some embodiments, which is used for the production of small or finely structured flat tubes 1 of this type, can therefore firstly be described as a precision engineered object (precision engineering). Secondly, however, the device according to some embodiments can also be used to produce flat tubes 1 with a corrugated inner insert c and wave heights d of greater than 10.0 mm using similarly thin sheet-metal strips a, b, c. The dimension D (width of the flat tube 1) can vary, for example, between approximately 12.0 and 150.0 mm.

In the exemplary embodiment according to FIG. 8, complete, i.e. finished flat tubes 1 having an inner insert c are perforated by means of the device P1. The flat tube contour is shown as a dotted line. Otherwise, this illustration corresponds to that from FIG. 3. As can be seen in FIG. 8, the perforation needles 20 pierce both wall parts a and b, and naturally also the inner insert c from opposite sides. As the illustration also shows, the needles 20 first of all pierce one wall part a or b between the wave crests/wave troughs of the inner insert c before the other wall part is pierced together with a wave crest/wave trough.

In contrast to the exemplary embodiment shown in FIG. 8, the perforation needles 20 can be arranged, in a further embodiment (not shown), in such a manner that the wall parts a and b are first pierced at the points 4 at which the latter bear against a wave crest/wave trough of the inner insert before the other wall part in each case is pierced. In other words, in such embodiments, the needles 20 of the upper row are located at those vertical positions 5 at which, in FIG. 8, the needles 20 of the lower row are located—and vice versa. In more precise terms, the rows of needles are offset by a needle 20. Although, in such embodiments, the wave flanks 13 could be compressed somewhat, it has been shown that the rigidity of the inner insert c in the flat tube 1 is of a magnitude such that satisfactorily neat, i.e. non-deformed tube ends can be produced.

If the device P1 according to FIG. 8 or according to related embodiments and according to corresponding methods production used, the perforating of individual sheet-metal strips can be omitted entirely. The design and the grinding of the perforation needles 20 can be adapted to the specific intended use of the device P1.

Various features and advantages of the invention are set forth in the following claims. 

1.-9. (canceled)
 10. A device useable as part of a production line for producing tubes from shaped sheet-metal strips, the device comprising: an upper die having a first row of punches; and a lower die having a second row of punches; wherein the first and second rows of punches form predetermined breaking points in at least one of the shaped sheet-metal strips, and wherein a punch of the second row of punches engages between two punches of the first row of punches.
 11. The device according to claim 10, wherein the predetermined breaking points comprise perforations.
 12. The device according to claim 10, wherein at least one of the shaped sheet-metal strips has a transverse corrugation defining a plurality of wave crests and wave troughs, and wherein the first row of punches acts in the wave crests and the second row of punches acts in the wave troughs.
 13. The device according to claim 10, wherein the two punches of the first row of punches each include a piercing tool.
 14. The device according to claim 13, wherein the piercing tool includes a perforation needle.
 15. The device according to claim 13, wherein the punch of the second row of punches includes a piercing tool.
 16. The device according to claim 15, wherein the piercing tool includes a perforation needle.
 17. The device according to claim 15, wherein the piercing tools of the two punches of the first row of punches are spaced apart a first distance, such that the piercing tools of the two punches of the first row of punches have the piercing tool of the punch of the first row of punches therebetween.
 18. The device according to claim 15, wherein at least one of the shaped sheet-metal strips has a transverse corrugation defining a plurality of wave troughs and wave crests, and wherein the piercing tools of the first row of punches pierce the wave troughs and the piercing tool of the second row of punches pierces the wave crests.
 19. The device according to claim 10, wherein the upper die includes a first roll and the lower die includes a second roll.
 20. The device according to claim 19, wherein the first roller defines an outer surface, the first row of punches extending across the outer surface, such that rotation of the first roller moves the first row of punches into and out of engagement with the at least one the shaped sheet metal strips.
 21. A production line for producing tubes from a first shaped endless sheet-metal strip, and a second shaped endless sheet-metal strip, the production line comprising: a first device including an upper die having a first row of punches; and a lower die having a second row of punches; wherein the first and second rows of punches form predetermined breaking points in the first shaped sheet-metal strip, and wherein a punch of the second row of punches engages between two punches of the first row of punches; a second device positioned at a common location along the production line with the first device, the second device operable to form predetermined breaking points in the second shaped endless sheet-metal strip; a first section upstream of the first device and the second device, the first section operable to shape the first and second shaped endless sheet-metal strips; and a second section downstream of the first device and the second device, the second section operable to combine the first and second shaped endless sheet-metal strips, wherein the first device and the second device work simultaneously to form the predetermined breaking points.
 22. The device according to claim 21, wherein the predetermined breaking points comprise perforations.
 23. A device useable as part of a production line for producing tubes from shaped sheet-metal strips, the device comprising: an upper die having a first wave shape; and a lower die having a second wave shape, wherein at least one of the shaped sheet-metal strips has a transverse corrugation substantially matching the first wave shape and the second wave shape, and wherein the upper die and the lower die produce predetermined breaking points in at least one of the shaped sheet-metal strips in the transverse corrugation without the corrugation being damaged.
 24. The device according to claim 23, wherein the predetermined breaking points comprise perforations.
 25. The device according to claim 23, wherein the upper die includes a knife and the lower die includes a roller.
 26. A method for producing tubes on a production line having rolls, the method comprising: shaping sheet-metal strips; combining the sheet-metal strips to form a tube; after shaping and combining, forming predetermined breaking points in the tube by contacting a first side of the tube with at least two punches from a first row of punches and contacting a second side of the tube with at least one punch from a second row of punches, wherein the at least two punches of the first row of punches have the at least one punch from the second row of punches therebetween.
 27. The method according to claim 26, further comprising severing individual tubes from the tube, wherein the tubes are severed along the predetermined breaking points.
 28. The method according to claim 26, wherein forming predetermined breaking points including forming perforations.
 29. The method according to claim 26, wherein contacting the tube first side includes inserting the two punches into respective wave troughs of the tube and wherein contacting the tube second side includes inserting the one punches into a wave crest of the tube. 